ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 29
RESONANT AND ANGLE-RESOLVED PHOTOEMISSION SPECTROSCOPY OF Ga
1−xMn
xSb
B.J. Kowalski1∗, R. Nietuby´c2,3, and J. Sadowski4,1
1Institute of Physics Polish Academy of Sciences, Al. Lotnik´ow 32/46, 02–668 Warsaw, Poland
2National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, ul. Gronostajowa 7/P–1.6, 30-387 Krak´ow, Poland
3National Centre for Nuclear Research, Andrzeja So ltana 7, Otwock- ´Swierk, Poland
4MAX-lab, Lund University, Box 118, SE–22100 Lund, Sweden
Keywords: synchrotron radiation, photoelectron spectroscopy, diluted magnetic semiconductors
∗e-mail : kowab@ifpan.edu.pl
Ga1−xMnxSb is a diluted magnetic semiconduc- tor exhibiting ferromagnetic properties, although at relatively low temperatures (TC = 2 K [1]). How- ever, it attracts interest due to the opportunity to study the interactions of magnetic ions with charge carriers in a host with anions chemically different than in Ga1−xMnxAs. The interaction between manganese atoms and surrounding anions influences strongly the details of the valence band structure.
Ga1−xMnxSb has also the band structure particu- larly suitable for making a novel device (like a fer- romagnetic resonant interband tunneling diode [2]).
Resonant and angle-resolved photoelectron spec- troscopies were applied in order to reveal the con- tribution of the Mn 3d states to the valence band of Ga1−xMnxSb. Since both techniques are based on use of synchrotron radiation, the experiments were carried out at the beamline 41 in the MAXlab syn- chrotron radiation laboratory of Lund University (Sweden).
The Ga1−xMnxSb layers with Mn contents in the range of 1 to 3 %, were grown on GaSb(100) substrates by molecular beam epitaxy (MBE) at low substrate temperature of about 230◦C. The growth was monitored by Reflection High Energy Electron Diffraction (RHEED). The 2-dimensional diffrac- tion patterns (streaks) and distinct RHEED oscil- lations were observed throughout the growth of the Ga1−xMnxSb layers up to their final thicknesses of 50 to 300 ˚A depending on the sample. The (100) surfaces of the layers exhibited also the Low Energy Electron Diffraction (LEED) patterns correspond- ing to the asymmetric (1 × 3) reconstruction.
No manifestations of secondary phases (like MnSb nanocrystals [3]) were detected on RHEED images after the growth. The absence of MnSb pre- cipitates in the investigated samples was confirmed also by a comparative study (including the sam- ples containing the precipitates) by scanning elec- tron microscopy.
The resonant photoemission experiment, carried out for photon energy range from 37 to 60 eV
(covering the Mn 3p-3d resonance), allowed us to identify the spectral feature corresponding to emis- sion from the Mn 3d states. The angle-resolved photoemission experiment, for photon energies from 50 to 106 eV enabled us to scan the band struc- ture along the [100] direction (in the normal emis- sion mode) as well as along the [011] direction (in the off-normal emission mode). The comparison of the experimental band structure diagram with the result of the resonant photoemission measurement showed that Mn 3d states contributed to a disper- sionless structure at the binding energy of 3.9 eV (with respect to the Fermi energy), revealed against a background of the host semiconductor bands cor- responding well to those reported in the literature for GaSb [4].
Acknowledgments: This research has received fund- ing from the European Community’s Seventh Frame- work Programme (FP7/2007-2013) under grant agree- ment no. 226716.
References
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[2] I. Vurgaftman, J.R. Meyer, “Ferromagnetic resonant interband tunneling diode,” Appl. Phys. Lett. 82 (2003) 2296.
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Phys. 109 (2011) 074308.
[4] G.E. Franklin, D.H. Rich, A. Samsavar, E.S. Hirschorn, F.M. Leibsle, T. Miller, T.-C.
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